At present, energy consumption caused by vehicles accounts for approximately a quarter of the overall energy consumption in the world. With the economic development in developing countries, the number of owned vehicles is increasing rapidly, and environmental and energy problems caused thereby become more serious. Due to the influence of oil crisis, developed countries have been developing energy saving technologies, aiming to keep the energy consumption of industrial sectors under the level of about half of the GNP. As the world is under the threat of both energy and environmental crisis, vehicle industry is demanded to improve the energy efficiency of vehicles and reduce emission of pollutants. However, it is difficult to solve this problem only by improving the performance of existing internal combustion vehicles. Developing electric vehicle is one of effective ways to solve this problem. A controller, which provides power supply to a drive motor in an electric vehicle and controls the magnitude and the power and direction of the current, is the core of the electric vehicle. In such a controller, switching elements for controlling the magnitude of power supplied to the drive motor and the direction of the current are usually a plurality of MOS transistors which control energizing current and armature current of the drive motor, and the magnitude of the power supplied to the drive motor is controlled by duty ratio of “turning on” and “turning off” the MOS transistors. The control signals for “turning on” or “turning off” these MOS transistors are generally pulse-width modulated signals having a high switching frequency, and thus these high power MOS transistors will generate heat. In order to resolve the problem that the temperature rise of the high power MOS transistors due to the generated heat is too grate, a plurality of MOS transistors of the same type and the same batch are connected in parallel on both the upper arm and the lower arm of the armature under large current, in which a radiator with large heat exchange area is mounted on the bodies of the MOS transistors. For a good overall performance in heat dissipation, economical efficiency and manufacturability, the radiator is generally made of aluminum or aluminum alloy. In the electric vehicle drive controller, the radiator is also used as conductors for connecting to the MOS transistors. In operation, an electrical vehicle drive controller with such a structure may have a great temperature rise. In existing practical products all over the word, the operating temperature of this kind of electrical vehicle drive controller raises to a maximum above 90□. The high operating temperature of the electrical vehicle drive controller affects not only the service life of its own, but also the reliability and security of the vehicle.